1. Field of the Invention
The invention concerns insertable probes, primarily in the surgical field, which can be steered or redirected after insertion. Several embodiments of the invention are in the form of steerable or flexibly curved microsurgical laser probes for use primarily in ophthalmic surgery. However, the invention also relates to insertable probes generally and has non-medical applications, for example, to non-medical endoscopy and boroscopy.
2. Background of the Related Art
A wide variety of surgical and diagnostic methods involve the insertion of probes, catheters, endoscopes and other devices into interior spaces and passageways within human or animal organs.
In the ophthalmic field, for example, intraocular laser photocoagulation, or the process of forming a blood clot in the interior of the eye using a laser, is performed in many types of surgical procedures. Application of laser photocoagulation is commonly done with the aid of a probe that carries an optical fiber that can direct the laser light. The fiber optic directs the laser energy from the laser source into the eye to the site of the coagulation. A typical prior art laser probe is shown in FIG. 1. Prior art probe 101 has a straight intraocular section 102 made from a straight metal sleeve. The metal sleeve covers the fiber optic 103 to protect the fiber optic 103. The guided laser output 104 exits the distal end 105 of the fiber optic 103 and impinges upon the coagulation site 106. Blood at the coagulation site 106 is coagulated by the energy transferred to that site by guided laser output 104.
Although easy to manufacture, there are shortcomings associated with the prior art laser probe. Surgical requirements limit how a laser probe 101 of the prior art can be inserted into the eye. When a laser probe 101 is inserted around insertion site 107 of the eye, the guided output 104 from the laser probe 101 cannot reach far periphery area 108 of the eye because the crystalline lens 109 of the eye blocks the range of motion of the laser probe 101. In fact, the furthest peripheral point toward the lens that the prior art laser probe 101 can reach is coagulation site 106 as shown in FIG. 1, when the probe comes into contact with the crystalline lens 109 at contact point 110. In addition to this limitation in reach, the laser probe 101 has an additional limitation that when the laser probe 101 is inserted at angle 111 as shown in FIG. 1, the intensity of the guided laser output 104 is reduced at coagulation site 106 because the guided laser output 104 is impinging on the coagulation site at a non-perpendicular angle 111. This reduction in intensity in turn reduces the effectiveness of the prior art laser probe 101. If, on the other hand, the guided laser output 104 could be made to be normal to the coagulation site 106, then the intensity of the guided laser output 104 would be at its maximum (for any given distance between distal end 105 and coagulation site 106) and the laser probe would be more effective.
In attempts to overcome these shortcomings, several variations of the metal sleeve laser probe of the prior art are in the field. There are curved laser probes made with a fixed and curved metal outer sleeve. These types of probes solve the problem of letting its guided laser output reach the far periphery of the eye. But unfortunately these probes can be used only with great difficulty in modern small incision vitrectomy surgery using cannulae. The cannulae used in vitrectomy surgery are typically straight cannulae that limit the passage of any curved probe or instrument. Even if the surgeon manages to force a curved laser probe through the cannula, the removal of the curved probe from the eye often causes the undesired effect of the cannula being removed from the eye as well. Another variation of the prior art laser probe uses a straight metal sleeve surrounding a fiber optic contained in a second metal tube having a curved contour. During surgery the outer sleeve is retracted allowing the inner sleeve to adopt a curved contour. But again, this type of laser probe is difficult to manipulate during surgery. There are additional shortcomings with this type of laser probe. For one example, it can curve in only one direction. For a second example, to remove the probe from the eye, the second metal tube must be manually straightened, necessitating awkward motions on the part of the surgeon and placing the eye at risk of inadvertent injury.
Another shortcoming common to all three types of prior art laser probes described above is that all of these laser probes employ a rigid metal outer sleeve that is potentially traumatic to delicate intraocular structures. Inadvertent contact with the lens or retina in particular can lead to serious physiological consequences.
Accordingly, the current state of intraocular laser probes is suboptimal and there is a need for a laser probe in which the angle or curvature of the optical fiber can be easily and quickly varied by the surgeon at will. Moreover, a device that solves the problems described above would have applicability in many other types of surgical and diagnostic procedures which involve the insertion of probes and the like into interior spaces and passageways within body organs of humans or animals, as well as corresponding non-medical mechanical applications.